Oh, that's the central system of the cluster, there's always a massive black hole orbited by many stars at the center of globular clusters and galaxies. At first I was like A 15-star system?! Then I looked at it. Yeah, that's totally normal, there are trillions of them in SE.

I thought there were 'only' about 100 billion galaxies in the universe and probably just a few hundred thousand or a few million in SE.

The SE universe is a cube 10 gigaparsecs on a side. There are probably at least 100 billion galaxies in SE, but assuming that there is only 10 billion (there is almost certainly many times that number), then you have 10 billion supermassive black hole systems, plus those of globular clusters, of which there can be 100+ per galaxy. So that is at least a trillion right there.

The SE universe is a cube 10 gigaparsecs on a side. There are probably at least 100 billion galaxies in SE, but assuming that there is only 10 billion (there is almost certainly many times that number), then you have 10 billion supermassive black hole systems, plus those of globular clusters, of which there can be 100+ per galaxy. So that is at least a trillion right there.

Either way, I'm still an idiot. Just after HD's response I went hunting and within maybe fifteen minutes I found another with 16. The point is that they're extremely common. I guess I was thrown by the fact that it was described as a multiple star system, and not being familiar enough with the program or astronomy I figured that was unusual. doh!

If you observe a black hole in reality (I don't hope this for you ), you will see just a non-distorded flare around the diverted position of the star, because the flare is created in the optical stuff, which is placed after the blach hole. In SE, the shape of the flare is distorded, it is not technically accurate, but kinda artistic. In your screenshot, there is another flare centered in the real position of the star, this happens when lens flares are in super.

Oh. This is a brown dwarf. To define it simply, it is the intermediate state between a star and a gas planet. Its light is reddish, and most of its energy is emitted by infrared light, that's why its appeat dark. So, this is not a bug. And also, welcome to the SE forum !